Hard alloys and method for producing the same



Patented Ap 1940 I HARD ALLOYS AND METHOD FOR PRODUCING THE SAME Walther Dawihl, Berlin-Kohlhasenbruck, and Karl Schriiter, Berlin, Germany, assignors to General Electric Company, a corporation of New York No Drawing. Application December 6, 1938, Se-

rial No. 244,222. In Germany January 11, 1938 8 Claims. (Cl. 106-1) Our invention relates to hard alloys and to a lively complicated o eover, it is diflicult to meth for producing th Same, I produce under these conditions tool bodies of any In the production of hard alloys used in the desired fi ation. cutting, that is, chip-removing and i th Therefore our invention has for its object to cutting shaping treatment carbides are used, as a produce carbides of metals of high melting point 5 rule, in particular carbides of metals of high melt- Showing great hardness d a s rengthfwithing point. Tool bodies of such carbides are probut any addition 0f auxiliary metal and at duced frequently b heating the carbides or carperatures far remaining below t e me t p t bide mixtures up to melting and allowing them to of the carbides, and, y, W hout Simulta- 10 solidify, under circumstances in suitable molds. neous application of mechanical AS 10 The shaped bodies thus obtained show a com- Sta-ted by exhaustive tests. s bject s ac ved paratively coarse-crystalline texture which preaccording to the invention y a P p l c n judice th ir use f many purposes c of several carbides of metals of high melting quently, shaped bodies have been prepared from P vizr'by admixing to a mixture-0f tungsten powdered carbid at r l temperature by carbide and tantalum carbide one or several car- 15 pressing which pressed bodies subsequently are bides of titanium, d ml va ad um, h strengthened merely by sintering. In order to bium, Zirconium thorium in quantiliy of more obtain with this method suflicient hardness of the than 5%, the mixture of tungsten Carbide and shaped bodies, the sintering frequently has been tantalum carbide amounting t e than 5 go raised up to close to the melting point of the car- 0f the alloy masso the De d ed m xture of bides. It ha appeared, however, i carrying on these carbides, after having been shaped in the this method in practice that an undesirable usual manner, can be P p bodies of V y coarsening of the grain of the material by crysat hardness and str n th y nt ine at talline transformation occurs .due to the mass Which bodies Owing to their finebeing heated up too close to the melting point, grained texture 0 high Cutting capa y a d 25 not to speak of the required high temperatures toughness. Best results are obtained if the quan which are difficult to govern b t h t be tity of the additional carbides amounts to from 10 served rather exactly. Therefore, the use of to sintered pure carbides and carbide mixtures has The reason for a mixture p d acc d n to been wholly given up in practice and the strength our invention Sintering S0 dense at the mp r 30 of the sintered shaped bodies has been improved tively low temperatures indicated might be due to by addition of more easily melting metals, othe chemical transformations of the simultanecalled auxiliary metals, whereby simultaneously 011813! Present tungsten carbide nd antalum carthe sinter temperature could be notably lo bide with the additional other carbide or carbides,

so, for example, the sintertemperatur ofa ixfor, tungsten carbide or tantalum carbide alone 35 ture of tungsten carbide and 5% cobalt is about 1 v n a m x f n n car ide and tanta- 1450 c. and thus is many hundred degrees lower lum ar ide req far higher t r t mp rathan the sinter temperature of tungsten carbide tures. The sam i the case w th other carnot containing such auxiliary addition. bides of metal-s of high melting point used besides 40 The addition of such auxiliary metals, however, tungsten Carbide and lu b d o prevents full utilization of the hardness of tungs- An hard alloy composed according to our ten carbide so that the resistance to wear of these invention and finished by sintering may have for carbides is not so high as that of carbides not conexample the following composition: taining auxiliary metal. Therefore one has looked out for ways how the high sinter tempera- Tungsten carbide Parts by i h; 45 tures required for pure carbides could be reduced, Tantalum carbidef 15 with simultaneous increase of the strength of the Titanium carbide f 15 shaped bodies. One of these ways, for example, consists in heating such carbides not containing The sinter temperature of this mixture lies at auxiliary metal with simultaneous application of 1550 C. and thus is about the same as the sinter 5o pressure, in order to obtain reduction of the temperature of the commercial hard metals consinter temperature. Furthermore, it has been taining auxiliary metals, such as tuangsten carproposed to favor the sinter efiect by the action of bide containing an addition of cobalt, and this high frequency currents during the application of temperature is by many hundred degrees lower pressure. These methods. however, are comparathan the sinter temperature of a single carbide. 55

A further example may be the following carbide mixture:

Parts by weight Tungsten carbide- 50 Molybdenum carbide 10 Ttantalum carbide 30 Vanadium carbide 10 The sinter temperature of this mixture lies at 1450" C., that is, it is likewise so low that a finegrained texture is obtained as it is required to achieve favorable mechanical properties.

Practical tests of the hard alloys produced according to our invention have shown that the alloys are remarkable for an extraordinarily low wear, for example when used as drawing dies or in the cutting treatment, such as in turning grey cast iron or hard and soft steels, so that tools manufactured from these alloys are very economice] in use.

"What claim and desire to secure by Letters Patent is:

1. The process of producing hard alloys consisting in preparing a powdered mixture of tungsten carbide and tantalum carbide, adding to this mixtiue at least one carbide of titanium, molybdenum, vanadium, niobium, zirconium or thorium in a quantity of more than 5%, the mixture of tungsten carbide and tantalum carbide amounting to more than 50% of the mass, pressing the mixture into shapes and sintering them at 1400-i700 C.

2. The process of producing hard alloys consisting in preparing a powdered mixture of timgsten carbide and tantalum carbide, adding to this mixture at least one carbide of titanium, molybdenum, vanadium, niobium, zirconium or thorium in a quantity of from 10 to pressing the mixture into shapes and sintering them at 1400-1700 C.

3. The process of producing a hard alloy, consisting in preparing a powdered mixture of '70 parts by weight tungsten carbide, 15 parts by weight tantalum carbide, and 15 parts by weight titanium carbide, pressing this mixture into shapes and. sintering them at 1550 C.

4. The process of producing a hard alloy consisting in preparing a mixture of 50 parts by weight tungsten carbide, parts by weight tantalum carbide, 10 parts by weight molybdenum carbide, and 10 parts by weight vanadium carbide, pressing the mixture into shapes and sintering them at 1450 C.

5. A sintered composition consisting of tungsten carbide and tantalum carbide and at least one carbide from the group consisting of titanium, molybdenum, vanadium, niobium, zirconium and thorium, the combined quantity of tungsten carbide and tantalum carbide being greater than of said composition and the material from said group comprising more than 5% of said composition.

6. A sintered composition consisting of a mixture of tungsten carbide and tantalum carbide and at least one carbide from the group consisting or" titanium, molybdenum, vanadium, niobium, zirconium and thorium, the metal from said group comprising 10 to 20% of said composition.

7. A sintered. composition consisting of tungsten carbide, 15% tantalum carbide and 15% titanium carbide.

8. A sintered composition consisting of 50% tungsten carbide, 30% tantalum carbide, 10% molybdenum carbide and 10% vanadium carbide.

wai'rrma ngiwnni. KARL sormorea. 

